You don't have to ask for permission regarding the route because it's your own creation, however, you do need to ask for permission to upload the custom assets.
I would have smoothed the terrain as well around the yard and station area. This is the only way to get the tracks to work and look right, and in particular the only way to avoid errors with the pro-track other than those caused by too tight a radius for switches. Unlike in real life, we also have to deal with most buildings not being embedded in the ground, and we don't need floating buildings and other assets!
I too use the YARN roads and LRW track. I like how the YARN and relations fit well on the ground and don't float above like the paper strip roads. The LRW track looks quite nice, although, the sleepers are a bit spread out for US standards. The thinner rail, however, does make the track look a bit older. You might want to customize some of the track to create sidings and other poor condition track for those under used places that get overgrown or rust over. Using some simple techniques, you can create variations that will suit your needs. I can help you with that if you wish. You would need permission, however, to include your customized assets your route so keep that in mind if you want to do that.